In dark days of Europe, which was a barren science, you saw the world through superstitions of alchemy and methods based on ignorance and speculation. A current of science emerged in medieval world that provided a new definition of science. In modern definition of science, it is knowledge of fixed truths of nature, man and society, which you have acquired with the tools of empirical intellect and by observation and induction, and which have been useful for ensuring the welfare and security of human beings. The background of this scientific current is call to reason, realism and philosophy. The intellect is source of knowledge of world, and the dimensions of the universe are based on principles of philosophy and method of realism. Sarton, leader of historiography of science in middle Ages, introduced Muslims as leaders of science in middle Ages. A collection of health, food, medicine and theoretical treatments is attributed to Muhammad, which has been published under the title of Prophetic Medicine. Ibn Khaldu criticized medicine of Prophet eight hundred years ago. he writes that Prophet was not a physician and a specialist in worldly affairs, and that use of Prophet's medicine does not require observance of status of prophethood The hypothesis of the present study is that despite Ibn Khaldun's criticism, the realism of the Prophet's medical works shows that Prophet's medicine needs new reflection and study, and a special type of medicine is based on trust in divine wisdom in creating an intelligent system between disease and medicine in nature. The present study has analyzed and explained realism in Prophet's medical words about fenugreek and has shown and proved it according to modern medical data. The Prophet issued a general decree regarding fenugreek and said; Hundreds of new laboratory and clinical research in medicine, veterinary medicine, agriculture, biology show general effectiveness of fenugreek in maintaining human health, livestock, nature and environment, and fenugreek is at heart of biology research, which Proves realism of comprehensive speech of Prophet.